Demon Deal
by TheBitterSea
Summary: Castle unexpectedly encounters Demon Dean on his quest to cure him. Dean has a surprising proposition. Slight season 10 AU. Destiel oneshot


Castiel had hit desperation days ago.

Ever since he'd gone his separate ways from Sam his search for Dean had become more and more frantic. He hadn't meant to cause Sam injury. He'd let his guard down for a moment, but it'd cost Sam the use of his arm for weeks. He wondered if Dean would be angry with him for it if they managed to find and cure him.

 _When._ Not if. _When_ they cure him.

Ever since Crowley somehow turned Dean into a demon Castiel's been at the end of his rope, unable to focus on anything but getting Dean back. It's how Sam got hurt. It's why Castiel was standing in an abandoned warehouse staring impatiently at the umpteenth demon he'd summoned, fiddling with his angel blade.

"So you don't know where he is?" he glared.

"I'm not saying I don't know where he is," the demon replied, fiddling nervously with his tie and glancing around, "I'm saying there'd nothing you could give me that would make ratting on him worth it."

Castiel narrowed his eyes and raised his angel blade, pointing it directly at the demon's throat. He didn't have the patience for this today. Summoning demons was something he never enjoyed, and Castiel was growing increasingly irate.

"Not even your life?" He threatened.

The demon shifted his weight from foot to foot, glancing behind him for the hundredth time before cautiously pushing the blade away from his throat.

"Look," he whispered, leaning towards Castiel, "You can't tell anyone I even talked to you, alright? You don't know what he's like. Death would be a gift compared to what he'll do to me."

Castiel remained silent, angel blade gripped by his side. The other demons had said similar things. Their information always proved to be a wild goose chase, so he wasn't feeling optimistic. Regardless, he had no intentions of letting this abomination live. Demons were a perversion of his father's creation, a disgusting stain on humanity.

His heart clenched when he thought of Dean. Crowley would pay for what he'd done.

The demon sighed, straightening his cuffs.

"Last I heard…" The demon cut himself off with a strangled cry and pointed behind the angel. Castiel whipped around to face the attacker as a blade flew past Castiel's head and embedded itself in the demon's chest. His heart skipped a beat when he recognized the intruder.

Dean laughed jovially as he walked past Castiel and pulled the First Blade from the demon's corpse.

"There's just no such thing as loyalty anymore, is there Cas?"

Castiel froze.

Dean looked exactly the same. Same cocky smile, same bowlegged stance, same everything. Castiel knew every inch of this body and soul; he had rebuilt each molecule himself. Seeing Dean again was like a breath of fresh air.

It was the eyes that kept Castiel frozen in place. A flash of black, empty as the night. Soulless orbs, sending a wave of dread through Castiel's body. Dean's eyes quickly returned to summer green, but Castiel did not relax. He knew what lay beyond those eyes, and it was not his Righteous Man. He'd thought he was prepared to face Dean, knowing what he had become.

He was wrong

"Still, it was a good throw," Dean continued speaking, either unaware or uncaring of the tornado of emotions crashing over the angel. Castiel strongly suspected the latter.

"Dean-" Castiel's voice was strained.

"What's the matter Cas? Aren't you glad to see me?" Dean took a step towards Castiel, twirling the first blade. "I hear you've been kicking up a storm trying to find me. You know I can't resist when you get all smitey," a wink, "Well here I am!" Dean flung his arms open in a mocking invitation.

"Dean, come with me. Come to the bunker." Castiel wished he had some way of restraining Dean. The demon handcuffs, a spell, anything. He wasn't sure if his fading angel strength was a match for a knight of hell. "Sam and I, we can fix you. We can-"

"I ain't broken, Cas." Dean interrupted, eyes flashing.

Castiel glanced to Dean's forearm. The Mark of Cain was covered by Dean's clothing, but Castiel could feel the evil emanating from it.

"The Mark. It's corrupted you. You wouldn't be this way if it weren't for Crowley-"

Dean cut him off with a wave of his hand.

"Don't bring your hate-on for Crowley into this." Dean smirked. "As for the Mark? All the Mark did to me was take away my inhibition. This is who I really am." Dean took a threatening step towards Castiel, still fiddling with the First Blade nonchalantly.

Castiel stood his ground. "You're wrong." He insisted. "Let us help you."

Green eyes surveyed him, and Dean seemed to be considering whether or not he'd like to murder his former best friend. Castiel wasn't even entire sure he could stop Dean if he decided to try.

After a long pause, Dean smiled mischievously and tucked the First Blade into the back of his jeans.

"You came here to make a deal with a demon did you not? How about you and me make a deal, Cas?" Dean stepped forward once more until he was less than a foot away from Castiel. His free hand came up to fiddle with the lapel of Castiel's trench coat.

Castiel stiffened. He hadn't really expected to make any headway in his quest to find Dean, and now here Dean was within arms reach. The angel was honestly a bit at a loss as to what he should do, and Dean's close proximity was a little overwhelming. He swallowed.

"I don't have a soul to trade, Dean." Castiel murmured, concealing his nervousness. Dean's face betrayed no emotion.

"I suppose you don't," Dean's hand moved to Castiel's tie, "but I want to know what you're willing to give up."

"Anything." Castiel's reply was immediate. He was determined to save Dean, no matter the cost. Wasn't that the goal? Despite his resolve, Dean's answering smile sent a chill down Castiel's spine.

"Your Grace? Your life?" Dean's breath ghosted Castiel's face.

"Anything." Castiel repeated. "If you come with me to the bunker and let Sam and I cure you, I'll give you anything you want." Blue eyes met green. Castiel could do this, for Dean. He'd die a thousand deaths if it meant saving Dean. The angel raised his hand, palm out. "Do we have a deal?"

Castiel barely had time to flinch as Dean's fist collided with his mouth and sent him tumbling to the ground. Castiel scrambled to get up, but Dean was faster, pinning him down before he could move. Perhaps Dean had decided he'd like to murder Castiel after all. The angel's heart sunk at the notion. Was it no less than he deserved, after everything he'd done to let Dean down?

"A handshake, Cas?" Dean teased in a surprisingly light tone, shaking his head lightly. "You of all people should know that crossroad deals are sealed with a kiss."

Castiel was suddenly acutely aware of the compromising position they were in. Dean was straddling Castiel's waist, and had both of Castiel's wrists pinned above his head. Was Dean really suggesting..?

A heat sprang unbidden to his groin. He had never been in such a position with Dean, but he couldn't deny that he'd desired it. Ever since he'd lain with April, Castiel had been fascinated by the idea of kissing Dean. He desperately wanted to be close to Dean in this way, but he knew in his heart this wasn't the real Dean. This Dean wasn't in his right mind, and kissing him would be wholly and completely wrong.

Dean seemed to take a sick pleasure from Castiel's conflicted expression. He released Castiel's wrists and threaded his fingers into the angel's hair, pulling his head back. Dean's other hand gripped him roughly by the throat.

"Pucker up, angel."

Dean's mouth smothered Castiel's protests. His lips pressed violently into Castiel's own, and Castiel found himself arching unbidden into the kiss. It was heady and hot and strangely metallic, and Dean's tongue felt both violating and arousing as it invaded his mouth. Castiel idly realized that Dean had bitten his lip so hard that he'd drawn blood.

Dean's body was pressed roughly against Castiel's, and as they kissed he could feel that Dean was extremely aroused. Castiel's head felt muddled. He could feel the wrongness of the kiss; Dean was too violent, too vindictive. Despite this, it still smelled and felt like Dean, and Castiel's body was responding in an embarrassingly human way. The angel groaned as Dean rubbed their groins against one another, moving his mouth to Castiel's neck and sucking roughly at the sensitive skin.

"De-an," Castiel moaned. This was so wrong. Castiel knew this was wrong. This wasn't Dean.

Dean pressed into him again and he barely suppressed another groan.

"Not complaining, are you Cas?" Dean murmured sarcastically.

Castiel attempted to compose himself as Dean began unfastening his tie.

"Our deal, Dean," Castiel breathed, pushing himself onto his elbows.

Dean stilled his hands, and leaned back to look Castiel in the eyes. Castiel just needed to get him to the bunker. To get him to Sam. Everything would be okay if he could just get Dean to Sam.

After a moment of deafening silence, Dean burst into cruel laughter. He shoved Castiel back onto the concrete floor and pushed himself up.

Castiel sputtered as Dean began to walk away, trying to ignore the sudden loss of Dean's body heat. He leapt up after Dean, clothes and hair in disarray.

"Dean! We made a deal!" Castiel cried after him. Even if it meant his life, Castiel would deliver Dean to Sam, to salvation. Dean turned his head and replied with yet another cruel laugh.

"I'm not a crossroads demon, Castiel. I don't make deals. But thanks for the kiss!"

Castiel sunk to his knees, and Dean was gone.


End file.
